Carbon and molybdenum electrodes employed in high-voltage devices such as ion sources and traveling wave tubes can be easily damaged by electrical breakdown and arcing events. Modification of the electrode surfaces due to these events can impact the voltage hold-off capability of the surfaces, which could lead to additional arcing, further damage, and the potential for device failure. Power suppli...
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In a wide variety of high-voltage applications surface flashover plays a major role in the system's performance and yet has not been studied in great detail for atmospheric conditions with modern diagnostic tools. Environmental conditions to be considered include pressure, humidity, and gas present in the volume surrounding the dielectric. In order to gain knowledge into the underlying process inv...
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A joint Argonne National Laboratory (ANL)/Naval Research Laboratory (NRL) program is under way to investigate X-band dielectric-loaded accelerating (DLA) structures, using high-power 11.424-GHz radiation from the NRL Magnicon Facility. DLA structures offer the potential of a simple, inexpensive alternative to copper disk-loaded structures for use in high-gradient radio-frequency (RF) linear accele...
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Experimental results are presented on the degree to which electrode surface conditioning and surface area impact the dielectric strength of water. The applied pulse to the test gap reached electric field levels greater than 1.5 MV/cm with risetimes around 200 and 50 ns, respectively. The test gap is composed of 304 stainless steel electrodes machined with a Bruce profile. Electrode surface roughne...
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When the performance criteria for a pulsed power generator is power density, and the duty cycle remains short ( s), then copper coils with an exciter are favored over permanent magnet rotors. If the permanent magnets are replaced with copper coils, steel, and an exciter, with the same total weight, the copper coil alternative will return a higher ma...
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A pseudospark-based high repetition rate pulse generator, together with a resonant charging power supply is presented. The pulse generator was developed for research applications that include transient plasma ignition. The design incorporates a lumped element Blumlein pulse-forming network that is switched by a commercial pseudospark into an output pulse transformer with a METGLAS core. The Blumle...
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The basic principles of high repetition rate nanosecond pulsed power supplies, the design, and the implementation are presented. Voltage pulses of 20–30 kV with a rise time of 30 ns, a pulse duration of 200 ns, a pulse repetition rate of 1–2 kHz, an energy per pulse of 0.5–1 J, and the average power up to 0.5–1 kW have been achieved with total energy conversion efficiency o...
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The system comprises either a nanosecond solid-state operating switch (SOS)-generator (see, e.g., Rukin, 1995) or a RADAN pulsed power source (see, e.g., Mesyats , 1993) that charges resonantly a short pulse-forming line (PFL) through a decoupling inductor, an active converter, a matched load, and several built-in voltage and current probes. The active converter comprises an additional 1-ns PFL ch...
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This paper describes a newly developed novel repetitive impulse voltage generator using a boost converter array. To solve problems such as short life time, low operating frequency, and the fixed pulse width of conventional generators, the proposed generator is designed with a boost converter array that employs series-connected capacitors and insulated gate bipolar transistors. The circuit can easi...
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Micrometer size plasmas, or microplasmas, find applications in pollution control, reduction, and prevention. The required nonthermal plasmas can be generated by either an electron beam or an electric discharge. The pulse widths and voltages necessary to generate these nonthermal plasmas are – , ...
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High-frequency multimegawatt polyphase resonant power conditioning techniques have recently been realized as a result of key component developments, cooperative efforts, research and development funding contracts, and newly applied engineering techniques. The first generation 10-MW pulsed converter-modulators, implemented at Los Alamos National Laboratory, Los Alamos, NM, are now utilized for the ...
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Results of tests of a fast-repetitive nanosecond modulator with a peak output power of 3 GW are presented. It comprises of a type S-5N charging driver, a power compressor based on a pulsed forming line, and a gas spark gap. The modulator has been designed for the formation of high-current electron beams and high-power microwave generation in a pulsed-repetitive regime. Excitation of 10-GHz microwa...
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For applications which require high peak current and fast rise time, silicon carbide (SiC) material is ideal because of its ability to tolerate high localized temperatures generated during switching. This research was performed to investigate SiC devices for pulse power applications and to analyze the failure of the devices. Seven 2 mm 2 mm SiC gate t...
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Compact high-action solid state switches are essential to weapon and protective systems for future Army vehicles. The Army Research Laboratory, Adelphi, MD, has been evaluating conventional and unconventional devices for an extended period of time. Large diameter thyristors have been explored and evaluated at currents in excess of 200 kA. Reverse dynistors, a Russian device, have shown even better...
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One of the promising designs of high-power nanosecond and subnanosecond pulse generators is based on the fast ionization dynistor (FID) stack triggered with nanosecond pulse of overvoltage. This pulse is usually formed by semiconductor opening switches. Delay time of these switches equals the sum of forward and reverse current pulse duration, i.e., several hundreds of nanoseconds. The novel openin...
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Many accelerators at Sandia National Laboratories utilize the Rimfire gas switch for high-voltage, high-power switching. Future accelerators will have increased performance requirements for switching elements. When designing improved versions of the Rimfire switch, there is a need for quick and accurate simulation of the electrical effects of geometry changes. This paper presents an advanced circu...
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The next linear collider (NLC) accelerator proposal at Stanford Linear Accelerator Center (SLAC, Menlo Park, CA), requires a highly efficient and reliable, low cost, pulsed-power modulator to drive the klystrons. A solid-state induction modulator has been developed at SLAC to power the klystrons; this modulator uses commercial high voltage and high current insulated gate bipolar transistor (IGBT) ...
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The fundamental limits on the volume and energy density of a pulse power that is to deliver a specific peak power pulse to a load depends upon the architecture of the system, the operational mode of the system, the energy storage geometries, the switching parameters employed, and the auxiliary equipment required. This paper examines these factors and develops the fundamental limits on the volume o...
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The structure of a compact air-cored high-voltage spiral strip pulse transformer is relatively simple, but considerable attention is needed to prevent breakdown between transformer windings. Since thickness of the winding conductors in the spiral strip type is in the order of submillimeter, field enhancement at the edges of the winding conductor is very high. It is, therefore, important to find pr...
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The Z machine at Sandia National Laboratories (SNL) is the world's largest and most powerful laboratory X-ray source. The Z Refurbishment Project (ZR) is presently underway to provide an improved precision, more shot capacity, and a higher current capability. The ZR upgrade has a total output current requirement of at least 26 MA for a 100-ns standard Z-pinch load. To accomplish this with minimal ...
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Radio frequency (RF) phase detector in 2856 MHZ based on personal computer is designed, built, and tested in support of free electron laser development based on 200-MeV RF linear accelerator in National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, which means for Chinese middle and long term development programme for basic research. The tested resolution ...
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